Mr. J. BlackwalFs Ornithological Notes. 375 



frosts were of frequent occurrence ; the maximum temperature 

 of the last week in that month, indicated by a pair of Rutherford's 

 horizontal self-registering thermometers exposed to the open air 

 in a shady situation, was 46°* 5, the minimum 22°, and the mean 

 36°, as recorded in my meteorological journal ; but in January 

 1827 the cold became intense; the temperature descended to 

 zero on the night of the 4th, and the mean for the month was 

 so low as 34°' 18. 



Notwithstanding the extreme severity of the season, the young 

 bird did not manifest the slightest symptom of torpidity, and on 

 the 12th of January I exhibited it at a meeting of the Literary 

 and Philosophical Society of Manchester, at which time it was 

 moulting, and in as good health apparently as birds usually are 

 when undergoing that process, a minute to that ejffect being en- 

 tered in the jom*nal of the proceedings of the Society by my friend 

 Mr. Peter Clare, who then officiated as secretary. Oq the 18th 

 of the succeeding February this young cuckoo died very sud- 

 denly, an event occasioned in all probability by exposm'e to severe 

 cold, for a Six's self-registering thermometer fixed in its cage 

 several days before indicated that the temperature had descended 

 to 31°; and though the bird had previously resisted the effects 

 of a much lower degree of temperature, yet it had not then made 

 such progress in moulting, and was therefore better protected, 

 being more completely covered with feathers. I may remark, 

 that in the year 1826, adult cuckoos disappeared from the 

 neighbourhood of Manchester in the first week of July, and that 

 young birds of the same species were not observed there after 

 the termination of August. 



Admitting the difficulty of proving a negative, still 1 am in- 

 clined to think that the experiment detailed above, when taken 

 in conjunction with others to be adduced hereafter, goes far to 

 establish the fact, that birds have not any physiological tendency 

 to torpidity. 



In advocating this view of the subject, I am aware that I 

 stand opposed to the high authority of Cuvier, who, in treating 

 upon the sand-martin, Hirundo riparia, in the first edition of the 

 ' Regne Animal,' tome i. p. 374, asserts, with reference to its 

 supposed torpor, that ^'^il parait constant qu'elle s'engourdit 

 pendant Phiver, et meme qu'elle passe cet etat au fond de Peau 

 des marais ;" and the same opinion is reiterated by Humboldt in 

 one of his published works ; but as I have not an opportunity of 

 referring to them at present, I cannot state in which. Both 

 these celebrated authors, however, have omitted to communicate 

 the particulars which led them to this conclusion, and the bare 

 assertion even of persons the most distinguished in the annals of 

 science cannot be received as equivalent to direct evidence ; more- 



